Dual repression by Fe2+-Fur and Mn2+-MntR of the mntH gene, encoding an NRAMP-like Mn2+ transporter in Escherichia coli
Dual repression by Fe2+-Fur and Mn2+-MntR of the mntH gene, encoding an NRAMP-like Mn2+ transporter in Escherichia coli
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DOI：
10.1128/jb.183.16.4806-4813.2001
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发表时间：
2001-08-01
影响因子：
3.2
通讯作者：
Hantke, K
中科院分区：
文献类型：
--
作者：
Patzer, SI;Hantke, K
Mn 2+是大肠杆菌中几种酶的辅因子，其摄取由质子依赖性金属转运蛋白MntH介导，MntH也以较低的亲和力识别Fe 2+。NntH属于真核生物Fe 2+和Mn 2+转运蛋白的NRAMP家族。在大肠在mntH与lacZ融合的大肠杆菌菌株中，Mn ~（2+）和Fe ~（2+）均能部分抑制mntH。Fur的失活导致Fe 2+依赖的mntH转录抑制的丧失，表明Fe 2+抑制依赖于全局铁调节剂Fur。然而，这些fur突变体仍然表现出Mn 2+依赖性的mntH抑制。Mn 2+反应转录调节mntH被确定为o 155的基因产物（重命名为MntR）。mntR突变体在Mn ~（2+）而非Fe ~（2+）对mntH转录的抑制中受损。纯化的MntR与mntH操纵子的结合是锰依赖性的。结合区域通过DNA酶I足迹分析定位，并且覆盖几乎完美的回文。通过体内操作者滴定测定，位于mntH操作者的22个核苷酸内的Fur结合位点类似于Fur框共有序列。
The uptake of Mn2+, a cofactor for several enzymes in Escherichia coli, is mediated by MntH, a proton-dependent metal transporter, which also recognizes Fe2+ with lower affinity. NntH belongs to the NRAMP family of eukaryotic Fe2+ and Mn2+ transporters. In E. coli strains with chromosomal mntH-lacZ fusions, mntH was partially repressed by both Mn2+ and Fe2+. inactivation of fur resulted in the loss of Fe2+-dependent repression of mntH transcription, demonstrating that Fe2+ repression depends on the global iron regulator Fur. However, these fur mutants still showed Mn2+-dependent repression of mntH. The Mn2+-responsive transcriptional regulator of mntH was identified as the gene product of o155 (renamed MntR). mntR mutants were impaired in Mn2+ but not Fe2+ repression of mntH transcription. Binding of purified MntR to the mntH operator was manganese dependent. The binding region was localized by DNase I footprinting analysis and covers a nearly perfect palindrome. The Fur binding site, localized within 22 nucleotides of the mntH operator by in vivo operator titration assays, resembles the Fur-box consensus sequence.